The rust fungi ( Pucciniales ) with 7000+ species comprise one of the largest orders of Fungi , and one for which taxonomy at all ranks remains problematic. Here we provide a taxonomic framework, based on 16 years of sampling that includes ca . 80 % of accepted genera including type species wherever possible, and three DNA loci used to resolve the deeper nodes of the rust fungus tree of life. Pucciniales are comprised of seven suborders - Araucariomycetineae subord. nov., Melampsorineae , Mikronegeriineae , Raveneliineae subord. nov., Rogerpetersoniineae subord. nov. , Skierkineae subord. nov ., and Uredinineae - and 18 families - Araucariomycetaceae fam. nov ., Coleosporiaceae , Crossopsoraceae fam. nov., Gymnosporangiaceae, Melampsoraceae , Milesinaceae fam. nov ., Ochropsoraceae fam. & stat. nov ., Phakopsoraceae , Phragmidiaceae , Pileolariaceae , Pucciniaceae, Pucciniastraceae , Raveneliaceae , Rogerpetersoniaceae fam. nov ., Skierkaceae fam. & stat. nov ., Sphaerophragmiaceae , Tranzscheliaceae fam. & stat. nov ., and Zaghouaniaceae . The new genera Araucariomyces (for Aecidium fragiforme and Ae. balansae ) , Neoolivea (for Olivea tectonae ), Rogerpetersonia (for Caeoma torreyae ), and Rossmanomyces (for Chrysomyxa monesis, Ch. pryrolae, and Ch. ramischiae ) are proposed. Twenty-one new combinations and one new name are introduced for: Angiopsora apoda , Angiopsora chusqueae, Angiopsora paspalicola , Araucariomyces balansae, Araucariomyces fragiformis, Cephalotelium evansii, Cephalotelium neocaledoniense, Cephalotelium xanthophloeae, Ceropsora weirii, Gymnotelium speciosum, Lipocystis acaciae-pennatulae , Neoolivea tectonae, Neophysopella kraunhiae, Phakopsora pipturi, Rogerpetersonia torreyae, Rossmanomyces monesis, Rossmanomyces pryrolae, Rossmanomyces ramischiae, Thekopsora americana, Thekopsora potentillae, Thekopsora pseudoagrimoniae, and Zaghouania notelaeae. Higher ranks are newly defined with consideration of morphology, host range and life cycle. Finally, we discuss the evolutionary and diversification trends within Pucciniales . Citation: Aime MC, McTaggart AR (2020). A higher-rank classification for rust fungi, with notes on genera. Fungal Systematics and Evolution 7: 21-47. doi: 10.3114/fuse.2021.07.02.

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Background and aims Plants are likely to invest in multiple defences, given the variety of sources of biotic and abiotic damage to which they are exposed. However, little is known about syndromes of defence across plant species and how these differ in contrasting environments. Here an investigation is made into the association between carbon-based chemical and mechanical defences, predicting that species that invest heavily in mechanical defence of leaves will invest less in chemical defence. Methods A combination of published and unpublished data is used to test whether species with tougher leaves have lower concentrations of phenolics, using 125 species from four regions of Australia and the Pacific island of New Caledonia, in evergreen vegetation ranging from temperate shrubland and woodland to tropical shrubland and rainforest. Foliar toughness was measured as work-to-shear and specific work-to-shear (work-to-shear per unit leaf thickness). Phenolics were measured as 'total phenolics' and by protein precipitation (an estimate of tannin activity) per leaf dry mass. Key results Contrary to prediction, phenolic concentrations were not negatively correlated with either measure of leaf toughness when examined across all species, within regions or within any plant community. Instead, measures of toughness (particularly work-to-shear) and phenolics were often positively correlated in shrubland and rainforest (but not dry forest) in New Caledonia, with a similar trend suggested for shrubland in south-western Australia. The common feature of these sites was low concentrations of soil nutrients, with evidence of P limitation. Conclusions Positive correlations between toughness and phenolics in vegetation on infertile soils suggest that additive investment in carbon-based mechanical and chemical defences is advantageous and cost-effective in these nutrient-deficient environments where carbohydrate may be in surplus.

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Background and aims In tropical lowland rain forest (TLRF) the leaves of most monocots differ from those of most dicots in two ways that may reduce attack by herbivores. Firstly, they are tougher. Secondly, the immature leaves are tightly folded or rolled until 50-100 % of their final length. It was hypothesized that (a) losses of leaf area to herbivorous invertebrates are generally greatest during leaf expansion and smaller for monocots than for dicots, and (b) where losses after expansion are appreciable any difference between monocots and dicots then is smaller than that found during expansion. Methods At six sites on four continents, estimates were made of lamina area loss from the four most recently mature leaves of focal monocots and of the nearest dicot shoot. Measurements of leaf mass per unit area, and the concentrations of water and nitrogen were made for many of the species. In Panama, the losses from monocots (palms) and dicots were also measured after placing fully expanded palm leaflets and whole dicot leaves on trails of leaf-cutter ants. Key results At five of six sites monocots experienced significantly smaller leaf area loss than dicots. The results were not explicable in terms of leaf mass per unit area, or concentrations of water or nitrogen. At only one site was the increase in loss from first to fourth mature leaf significant (also large and the same in monocots and dicots), but the losses sustained during expansion were much smaller in the monocots. In the leaf-cutter ant experiment, losses were much smaller for palms than for dicots. Conclusions The relationship between toughness and herbivory is complex; despite the negative findings of some recent authors for dicots we hypothesize that either greater toughness or late folding can protect monocot leaves against herbivorous insects in tropical lowland rain forest, and that the relative importance varies widely with species. The difficulties of establishing unequivocally the roles of leaf toughness and leaf folding or rolling in a given case are discussed.

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Background and aims Plant cyanogenesis is the release of toxic cyanide from endogenous cyanide-containing compounds, typically cyanogenic glycosides. Despite a large body of phytochemical, taxonomic and ecological work on cyanogenic species, little is known of their frequency in natural plant communities. This study aimed to investigate the frequency of cyanogenesis in Australian tropical rainforests. Secondary aims were to quantify the cyanogenic glycoside content of tissues, to investigate intra-plant and intra-population variation in cyanogenic glycoside concentration and to appraise the potential chemotaxonomic significance of any findings in relation to the distribution of cyanogenesis in related taxa. Methods All species in six 200 m(2) plots at each of five sites across lowland, upland and highland tropical rainforest were screened for cyanogenesis using Feigl-Anger indicator papers. The concentrations of cyanogenic glycosides were accurately determined for all cyanogenic individuals. Key results Over 400 species from 87 plant families were screened. Overall, 18 species (4.5 %) were cyanogenic, accounting for 7.3 % of total stem basal area. Cyanogenesis has not previously been reported for 17 of the 18 species, 13 of which are endemic to Australia. Several species belong to plant families or orders in which cyanogenesis has been little reported, if at all (e.g. Elaeocarpaceae, Myrsinaceae, Araliaceae and Lamiaceae). A number of species contained concentrations of cyanogenic glycosides among the highest ever reported for mature leaves-up to 5.2 mg CN g(-1) d. wt, for example, in leaves of Elaeocarpus sericopetalus. There was significant variation in cyanogenic glycoside concentration within individuals; young leaves and reproductive tissues typically had higher cyanogen content. In addition, there was substantial variation in cyanogenic glycoside content within populations of single species. Conclusions This study expands the limited knowledge of the frequency of cyanogenesis in natural plant communities, includes novel reports of cyanogenesis among a range of taxa and characterizes patterns in intra-plant and intra-population variation of cyanogensis.

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1. The effect of male tree density on pollen flow and fruit set in females was examined for three species of dioecious tree (Neolitsea dealbata, Litsea leefeana and Diospyros pentamera) in complex notophyll rain forest in tropical, northeastern Australia. 2. The spatial distribution for all reproductive individuals combined was significantly clumped in Diospyros but not in either Litsea or Neolitsea. Separate male and female groups were significantly clumped in all species. More than 80% of nearest male neighbours occurred within 10m of Neolitsea females and within 20m of Litsea and Diopsyros females. The ratio of males to females was 1.6:1 (Neolitsea), 1.5:1 (Diopsyros) and 1.3:1 (Litsea). 3. No species produced fruit asexually when flowers were isolated in mesh bags. All species populations flowered synchronously but Diopsyros flowered for a longer period (15 weeks), than either Neolitsea (3-4 weeks) or Litsea (4-5 weeks). All species had small, unspecialized flowers and were pollinated by small, generalist insects. Male trees produced more flowers per reproductive shoot than females and flower production was positively correlated with tree size in males but not in females. Fruit set was not correlated with tree size in female trees. 4. The ratio of fruit set to flowers in females was negatively related to two measurements of male to female distance (distance to the nearest male tree (all species) and mean distance to the nearest 10 (Neolitsea and Diospyros) or three (Litsea) males, termed 'local male distance'). The rate of reduction in fruit set with increasing nearest male distance was the same for all species, although Diospyros produced a higher proportion of fruit relative to flowers. The ranges of fruit set for Neolitsea, Litsea and Diospyros were 1-30%, 2-20% and 20-40%, respectively. Fruit set in Neolitsea females was similar in two successive seasons, indicating a consistent effect of local male distance on fruit set. 5. The amount of pollen trapped at female trees over the whole flowering season was unrelated to fruit set or to local male distance in all species. Amounts of pollen trapped at females after the first 6 (Neolitsea) and 15 (Diospyros) days of flowering were negatively correlated with local male distance. In Neolitsea females, the amount of pollen trapped at females after 6 days of flowering was positively related to fruit set, indicating that effective fertilizations occur early in the flowering period. 6. Although the mechanism for density-dependent pollen movement is the same for all three species, the longer flowering period and more gradual production of flowers found in Diospyros allowed more time for pollen to move through the population. It is concluded that rain-forest trees which have obligate outcrossing breeding systems, brief, synchronous flowering periods and are pollinated by a non-specialized fauna risk reduced rates of fruit set when relatively isolated from conspecifics.

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